Air compressor



A. J RIX AIR COMPRESSOR Sept. 5, 1933.,

Filed Feb. 9, 1952 3 Sheets-Sheet 1 IN! "EN TOR.

BY A T A 7 TYR V QYS Sept. 5, 1933. A. J. RIX I 1,925,544

AIR COMPRESSOR Filed Feb. 9, 19:52 3 Shets-Sheet 2 Fig. r2.

INVENTOR.

M ZW

A T 72155 S.

Sept. 5, 1933. A. J. RIX 1,925,544

AIR COMPRESSOR Filed Feb.- 9, 1932 3 Sheets-Sheet 3 INVENTOR.

@ J/ BY p W v Q/ mf/MMV Ma??? Patented Sept. 5, 1933 STATES .PATEN Thisinvention relates to air compressors, and particularly to improvementsin the valve mechanism shown in my Patent Number 1,819,691 entitled Aircompressor i sued August 13th,

The valve mechanism disclosed in the patent above referred to embodiesan inlet and a discharge valve of a poppet valve type, said valves beingnormally held in closed position by springs and being'mechanicallyactuated to insure positive opening anclclosing of the same. Valves ofthis type are fairly heavy and as compressors of this character operateat high speeds, such as 1000-R1.'P. M. or greater, inertia forces of anexcessive nature are produced causing hammer action of the valves,spring breakage, excessive wear, etc., this being particularly true ofthe discharge valves as they are heavier due-to the differentialcounter-pressure pistons employed.

The object of the .presentinvention is togenerally improve and simplifythe construction and operation of'valve mechanisms of thecharacterdescribed, and particularly to provide a differential pressurecounter-balanced discharge valve adapted: to be automatically openedduring the compression stroke of the compressor by the pressure of thefluid compressed during the compression stroke, and to providemeans forpositively closing the discharge valve by cam action or the like duringthe suction stroke.

The compressor, together with the valve mechanism employed, is shown byway of illustration in the accompanying drawings, in which Fig. 1 isaside elevation of a direct connected engine and air compressor, saidside elevation being partially broken away and sectioned to show certainparts of the mechanism.

Fig. 2 is a vertical cross section of one of the air compressingcylinders.

Fig. 3 is an enlarged detail section of the discharge valve and a partof its actuating mechanism.

Fig. 4 is a section similar to Fig. 3, showing a modified form of thedischarge valve and actuating mechanism.

Fig.5 is an enlarged view of the cam whereby the discharge valve ismechanically closed.

Fig. 6 is an enlarged view of the. double lobe r cam whereby the inletvalve is actuated.

Referring to the drawings in detail, and particularly Fig. 1, Aindicates the cylinders of an internal combustion engine of the fourcylinder type, B the crank shaft, and C the cam shaft which, in thisinstance, is driven from the crank shaft by gears 2 and 3 in the usualmanner to maintain a speed ratio between the crank and cam shafts of twoto one. The crank case generally indicated at D, which supports thecylinders A and the crank shaft B, is in this instance extended tosupport a pairof compressor cylinders generally indicated at E and F.Each cylinder is provided with a piston, such as shown at 5, and as thecrank shaft B is extended to provide two additional cranks, such asshown at 6 and '2, the pistons 5 will be connected through rods 8 withthe respectivecranks and as such will operate in unison with the pistonsand the cylinders indicated at A.

The compressor cylinders E and F are identical in construction. They areboth provided with inlet and discharge valves, such as indicated at 9and 10 respectively. The inlet valve is mechanically operated to insurepositive opening and closing of the same, while the discharge valve isautomatically and pneumatically opened during the compression stroke ofthe compressor and mechanically closed during the suction stroke.

- The valves employed are of the poppettype, such as used in automotivepractice, the inlet valve being opened inwardly in the usual man ner andbeing operated by a rocker arm 9a. The rocker arm is operated by apusherrod, such as shown at 11, and this is, in turn, actuated by the extendedcam shaft C, which is identical to any ordinary cam shaft with theexception that double lobe cams such as shown at- 12 are employed inconnection with the inlet valves, while cams of the concave type, suchas shown inFig. 5, are employed in conjunction with the dischargevalves. Double lobe and double concave cams are required due to the factthat the cam shaft operates at a one to two ratio, as the valves must beopened and closed once during each revolution of the crank shaft whilethe valves on-the engine proper are merely opened once during tworevolutions of the crank shaft.

The discharge valves 10, together with the mechanism actuating the same,form the subject matter of the present application and are bestillustrated in Fig. 3. By referring to this figure and Fig. 2, it willbe noted that the valves are of the poppet valve type and that they openoutwardly with relation to the cylinder. The head G of the cylinder isprovided-with discharge passages 14 which are connected in any suitablemanner with a receiver, not here shown, and when valves 10 are openedduringthe discharge stroke of the main pistons air will enter thepassages 14 and discharge therefrom into the receiver. Necessarypressure will, however, always be maintained in the discharge passages14 and means must accordingly be provided forcounter-balancing thepressure exerted on top of the valves 10 as the pressure in the passages1 will often exceed one hundred pounds gauge or more per square inch ofexposed valve area. To counter-balance this pressure the heads G areprovided with cylinders, such as indicated at 15, and each cylindercarries a piston 16. The pistons are welded, or otherwise secured, tothe stems 17 of the valve 10 as indicated at 18 and as such move inunison with the valves 10 whether these are opened or closed. Thepistons 16 are provided with rings, such as shown at 16a, to reduceleakage to a minimum and they are suitably lubricated through an annularsurrounding passage, such as shown at 19. The pistons 16 present an areaslightly less than the area presented by the valves 10 so that thepressure within the passages 14 will be sumcient to maintain the valvesclosed or on their seats, hence eliminating the necessity of employingany springs for this purpose.

The discharge valves 10 are, as previously stated, adapted to beautomatically and pneumatically opened by air pressure and, conversely,to be mechanically closed. Each valve 10 is accordingly provided with arocker arm 20 pivotally supported on top of the head GQas indicated at21. Each rocker arm is provided with a pusher rod and tappet, such asindicated at 22, and the pusher rods are, in'turn, actuated by theconcave cams indicated at 23, these cams permitting automatic opening ofthe valves and at the same time providing the means whereby the valvesare mechanically and positively closed during the suction stroke. Aspring 24 is interposed between each rocker arm 20 and the head G andthe function of these springs will hereinafter be described.

In actual operation the inlet valves will function in the usual manner,that is, they are actuated by the double lobe cams and as such will beopened during the suction stroke of the pistons and will beautomatically closed by means of the springs during the compressionstroke. The discharge valves 10, on the other hand, will function in anentirely different manner, as they are automatically and pneumaticallyopened. This is accomplished as follows: When the main pistons traveldownwardly during the suction stroke, the inlet valves are opened andthe cylinders are filled with air or any other fluid to be compressed.During the upward or compression stroke the inlet valves close and theair or fluid, which has previously entered, will accordingly becompressed and when a predetermined pressure is reached, depending uponthe diiTerence in area between the valves 10 and the counter-balancingpistons 16, valves 10 will open due to the fluid pressure exerted ontheir lower surfaces. The concave portions of the cams, indicated at 26,will at this time register with the pusher rods 22, hence permitting thevalves 10 to open by air pressure and to transmit movement through therocker arms 20 to force the pusher rods downwardly toward the bottom ofthe concaves 26. The moment the air or fluid has been discharged, theopposite sides of the concaves, indicated at 27, engage the pusher rodsand the valves 10 are, accordingly, positively closed, and when closedwill remain closed due to the air pressure in the discharge passages 14and also due to the rounded contour portions 28 of the earns 23. Hence,

it will be noted that the discharge valves are automatically opened bythe pressure of the fluid being compressed during the compression strokeand that they are mechanically closed by the cam portions 27 during thecommencement of the suction stroke. The automatic opening of the valvesby the pressure produced Within the cylinders is of great importance asit permits opening of the valves before the air pressure within thecylinders becomes very great, hence permitting the valves 10 to openslowly as the pressure builds up thereby reducing inertia forces to aminimum.

Compressors of this character are usually provided with an unloadermechanism and, as any desired type of unloader mechanism may beemployed, specific description thereof is thought unnecessary. Sufficeit to say, that when the unloader mechanism operates, the inlet valvesare maintained in open position permitting the air or fluid to becompressed and to enter and freely discharge, or in other words to surgeback and forth between the inlet valves. Under such conditions, thedischarge valves 10 here shown will not open as compression pressure isnot produced in the compressing cylinders. The cam shaft, however,continues operation and the rocker arms and pusher rods 22 whereby thedischarge valves are operated would accordingly have a tendency to jumpand hammer with relation to the cavities 26 formed in the cams 23, saidjumping or hammering is entirely avoided in the present instance byintroducing the springs 24, as the tension thereof will cause the rockerarms and pusher rods to follow the contour of the cams 23 just as surelyas if the valves 10 were being operated.

While diilerential'pistons 16 are shown in the main views of thedrawings, it is obvious that similar results maybe obtained by the useof a flexible diaphragm, such as indicated'at 16a in Fig. 4. This typeof diaphragm permits opening and closing of the valve and permitscounter loo ill)

balancing of the same and as such functions substantially in the samemanner as the piston 16; and while other featuresof the invention aremore or less specifically described and illustrated, I wish itunderstood that various changes may be resorted to within the scope ofthe appended claims. Similarly, that the materials and finish of theseveral parts employed maybe such as the manufacturer may decide, orvarying con ditions or uses may demand.

Having thus described my invention, what I ice with. a receiver so as tocontainfluid under receiver pressure, a discharge valve in the head andinterposed between the cylinder and the discharge passage, said valvebeing mechanically closed and being maintained in closed position bymechanical means and also by the fluid pressure in the dischargepassage, means cooperating withthevalve I charge passage formed thereinin communication with the receiver so as to contain fluid under receiverpressure, a discharge valve in the head and enclosed between thecylinder and the discharge passage, a piston in the cylinder adapted tocompress fluid and by compression of the fluid adapted to open thedischarge valve against the fluid pressure in the discharge passage,means on the valve for partially counter-balancing the fluid pressure inthe discharge passage and mechanical means for closing the valve.

3. An air compressor comprising a cylinder and a head, a piston in thecylinder, a crank shaft whereby reciprocal movement is transmitted tothe piston, a cam shaft driven by the crank shaft, an. inlet and adischarge valve in the head and communicating with the cylinder, adouble lobe cam whereby the inlet valve is opened during each suctionstroke of the piston, said discharge valve adapted to be pneumaticallyopened during each compression stroke of the piston, and a cam on thecam shaft having a pair of depressions formed therein permittingpneumatic opening of the discharge valve said cam also functioning topositively close the discharge valve during each suction stroke of thepiston.

In a compressor of the character described, a cylinder and a head, saidhead having a discharge passage formed therein, and adapted tocommunicate with a receiver so as to maintain recured on said stem andhaving an area slightly 7 less than the area presented by the valve soas to partially counter-balance pressure on the valve, and means forpositively closing the valve during each suction stroke of the piston.

5. In a compressor of the character described, a valve, a seat withwhich it cooperates,'a stem on the valve, said valve formingcommunication between a cylinder and a discharge passage in which ismaintained receiver pressure, a piston secured to the stem of the valveand having an area slightly less than the area of the valve, said pistonbeing exposed to receive pressure so as to partially counter-balancepressure against the valve, a rocker arm cooperating with the stem, anda cam whereby the rocker arm is actuated, said cam having a depressionformed therein permitting pneumatic opening of the valve and saiddepression also functioning to positively close the

